In the electron guns employed in cathode ray tubes it is conventional practice to mount the cathode in a multi-diametered, substantially tubular cathode eyelet. The cathode, which also is generally tubular, is welded to the smaller diametered end of the eyelet. To insure ease of insertion of the cathode into the eyelet the eyelet diameter has been made slightly larger than the diameter of the cathode. Such an arrangement is illustrated in FIGS. 1 and 2 herein.
A second eyelet configuration which has been used is shown in U.S. Pat. No. 3,351,792. Herein the eyelet portion which is to be attached to the cathode is substantially triangular in configuration. Again, to assure reasonable insertion, some dimensional tolerance must be employed. These tolerances make it difficult to maintain the cathode in a critical spacing with the first grid of the electron gun until affixation can be accomplished. Reducing the diameter of the eyelet to more closely match that of the cathode, for example, to make a frictional engagement, introduces insertion problems; further, the friction fit can harm the delicate potentially emissive material which is attached to the insertion end of the cathode.